Modern sonography makes possible the detection of small and subtle changes in the normal echo pattern. These may represent significant pathological changes which can not al­ ways be fully revealed by the echo pattern alone. There is, therefore, an increasing need for the supplement of the ultra­ sonically guided percutaneous puncture, which can be per­ formed with great accuracy and with virtually no risk. Also, ultrasonically guided puncture has proven invaluable for a wide variety of therapeutic purposes. The first percutaneous puncture guided by ultrasonic scanning using a specifically designed transducer was per­ formed in 1969 at the ultrasonic laboratory in Gentofte, now Herlev, Hospital, Copenhagen. The idea was based on a punc­ ture transducer described and used by Kratochwill for punc­ ture under the guidance of the ultrasonic A-presentation tech­ nique. The development in the field formed the basis of the First International Conference on Ultrasonically Guided Puncture at Herlev Hospital in 1978 sponsored by The Danish Society of Diagnostic Ultrasound. The knowledge and experience of the speakers at that conference was compiled in the book "Ultrasonically Guided Puncture Technique" published in 1980. Since then the Society has sponsored a conference at the same place in 1980 and 1983, the latest conference being termed "Third International Conference on lnterventional Ultrasound".